To meet the demand for wireless data traffic having increased since deployment of fourth generation (4G) communication systems, efforts have been made to develop an improved fifth generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘beyond 4G network’ or a ‘post long term evolution (LTE) system’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation and the like.
In the 5G system, hybrid frequency shift keying (FSK) and Feher's quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
With the popularization of smartphones, data traffic is increasing rapidly. The increasing number of smartphone users spurs the consumption of smartphone-based application services such as social network services (SNSs) and games, resulting in an unprecedented increase in data traffic. Of particular concern, beyond person-to-person communication, if machine intelligence-based communications, such as person-to-machine and machine-to-machine communications, are activated as a new field of technology, traffic concentrations at base stations will increase too dramatically to accommodate the increased demand.
There is therefore a need of a technology to accommodate increased traffic, and direct communication between devices is coming into the spotlight as such a technology. This technology, so called D2D communication, is promising for licensed band communication systems such as cellular communication systems and unlicensed band communication systems such as wireless local area network (WLAN) systems.
LTE-based D2D communication is characterized by D2D discovery and D2D communication. D2D discovery is a process in which a user equipment (UE) checks identities or interests of other proximally located UEs, or advertises its identity or interests to other proximally located UEs. At this time, the identity and interests may be represented by a UE identifier (ID), an application identifier, or a service identifier. Further, the identities and interests can be variously configured depending on the D2D service and operation scenario.
In order to support D2D operation between D2D, UEs located in different cells in an asynchronous network, it is necessary to perform a synchronization procedure between the Tx and Rx D2D UEs. For this purpose, the Tx D2D UEs located in the respective cells transmit a D2D synchronization signal (D2DSS). There is therefore a need to implement rules for determining the D2DSS transmission timing, D2DSS Tx UE, and resources for D2DSS transmission. In a case where a plurality of UEs transmit D2DSS, an Rx UE may receive diverse D2DSSs. Accordingly, it is necessary to determine the timing and resources for transmitting each D2DSS. In a case of the LTE-based D2D system, this determination must be in compliance with the resource allocation and transmission rules of the LTE system.
However, no specification on D2DSS transmission timing and resource utilization of the D2D Tx UE has yet been proposed. Furthermore there is a need of specifying the operation of the D2D Rx UE in association with a Type 2B discovery transmission timing and a Mode 2 communication transmission timing configuration. However, there is currently no method specified for implementing such mechanisms.
There is therefore a need to specify resource allocation for synchronization between transmitter and receiver and operation of the receiver according to the determined transmission time and transmission timing in the system supporting D2D communication.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.